I would also very, very strongly suggest finding a Snap-On truck and buying an 11 mm wrench, p/n RXSM11B, which is sold individually. It's a crescent on one end and a flare-nut on the other, both of which you will use. Snap-On is the most precisely and rigid made wrench there is -- unfortunately, Volvo brake line fittings are relatively soft and the nuts, if stubborn* (which you can count on given their age), round easily if the wrench has even the slightest slop. But when you put the Snap-On wrench on it, you'll immediately feel how slop-free the nut-wrench match is.
Yeah, the price is high for a single wrench, but the benefit is worth the price -- you'll thank me :-).

* by the way, pretreat (many applications over many hours) with PB-Blaster to lessen their stubbornness.

Good luck.